Electric chemical capacitors such as electric double layer capacitors and so on can be made smaller in size and lighter in weight easily. Therefore, electric chemical capacitors are expected, for example, as backup power supplies for portable equipment (miniature electronic equipment) or the like, auxiliary power supplies for electric vehicles or hybrid vehicles, etc. Thus, various examinations have been made to improve the performance of the electric chemical capacitors. A typical electric chemical capacitor has a laminated structure in which a separator is put between electrodes (electric chemical capacitor electrodes) each including a collector and a polarized electrode layer formed thereon. When high capacitance is required in an electric vehicle power supply, it is typical to use a structure in which a large number of such electrodes are laminated through separators (see Patent Documents 1 and 2).
[Patent Document 1] Japanese Patent Laid-Open No. 2001-250742
[Patent Document 2] Japanese Patent Laid-Open No. 2001-284184
The capacitance of an electric chemical capacitor depends largely on the area of a polarized electrode layer included in each electrode. In order to increase the capacitance of the electric chemical capacitor, it is therefore preferable to set the area of the polarized electrode layer to be as wide as possible.
However, a part of the collector may be used as an extractor electrode or the like. In this case, when the area of the polarized electrode layer is set to be too wide, an area available as the extractor electrode is so insufficient that it is difficult to assemble the electric chemical capacitor. Accordingly, in order to secure the capacitance as large as possible without spoiling the easiness to assemble, it is important to accurately control the position where the polarized electrode layer is formed on the collector.
On the other hand, in some electrodes for use in electric chemical capacitors, an undercoat layer serving as an adhesive layer may be provided between a collector and a polarized electrode layer so as to enhance the adhesion strength therebetween. A high-conductivity material is generally used for such an undercoat layer in order to prevent the resistance value from increasing. The undercoat layer is a layer for bonding the collector layer and the polarized electrode layer with each other. It is therefore necessary to set the region where the undercoat layer is provided to be equal to or wider than the region where the polarized electrode layer is provided.